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x/4 = 15/12 - 13/20
x/4 = 3/5
x = 3/5 . 4
x = 12/5
Vậy x=12/5
Tk mk nha
\(\frac{15}{12}-\frac{x}{4}=\frac{13}{20}\)
\(\frac{x}{4}=\frac{15}{12}-\frac{13}{20}\)
\(\frac{x}{4}=\frac{3}{5}\)
\(\Rightarrow x=2,4\)
\(\frac{15}{17}x\frac{45}{13}-\frac{15}{17}x\frac{10}{13}-\frac{9}{13}x\frac{15}{17}-\frac{15}{17}\)
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\(=\frac{15}{17}x\left(\frac{45}{13}-\frac{10}{13}-\frac{9}{13}-1\right)\\ =\frac{15}{17}x1=\frac{15}{17}\)
\(\frac{15}{17}\times\frac{45}{13}-\frac{15}{17}\times\frac{10}{13}-\frac{9}{13}\times\frac{15}{17}-\frac{15}{17}\)
\(=\frac{15}{17}\times\left(\frac{45}{13}-\frac{10}{13}-\frac{9}{13}-1\right)\)
\(=\frac{15}{17}\times1\)
\(=\frac{15}{17}\)
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\(\left(2.8x-32\right):\frac{2}{3}=90\)
\(2.8\cdot x-32=90\cdot\frac{2}{3}\)
\(\frac{14}{5}x-32=60\)
\(\frac{14}{5}x=60+32\)
\(\frac{14}{5}x=92\)
\(x=\frac{230}{7}\)
B , c , d tương tự
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1.
a) \(\frac{16}{24}-\frac{1}{3}=\frac{16}{24}-\frac{8}{24}=\)\(\frac{8}{24}=\frac{1}{3}\)
b) \(\frac{4}{5}-\frac{12}{60}=\frac{48}{60}-\frac{12}{60}=\frac{36}{60}=\frac{9}{15}\)
3.
a)\(\frac{17}{6}-\frac{2}{6}=\frac{17-2}{6}=\frac{15}{6}\)
b) \(\frac{16}{15}-\frac{11}{15}=\frac{16-11}{15}=\frac{5}{15}=\frac{1}{3}\)
c) \(\frac{19}{12}-\frac{13}{12}=\frac{19-13}{12}=\frac{6}{12}=\frac{1}{2}\)
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\(a.\) \(\frac{4}{15}.\frac{7}{9}+\frac{4}{15}.\frac{2}{9}\)
\(=\frac{4}{15}\left(\frac{7}{9}+\frac{2}{9}\right)\)
\(=\frac{4}{15}.\frac{9}{9}\)
\(=\frac{4}{15}.1\)
\(=\frac{4}{15}\)
\(b.\) \(\frac{13}{19}.\frac{23}{11}-\frac{13}{19}.\frac{8}{11}-\frac{13}{19}.\frac{4}{11}\)
\(=\frac{13}{19}\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)
\(=\frac{13}{19}.\frac{11}{11}\)
\(=\frac{13}{19}.1\)
\(=\frac{13}{19}\)
a)4/15 x(7/9+2/9)=4/15x1=4/15
b)13/19x(23/11-8/11-4/11)13/19x1=13/19
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Ta có :
10 : 5 = 2
Mẫu x 2 thì tử cũng x 2 để ra phân số bằng phân số đó
Ra số cần điền tiếp theo là 4 ( 4/10 )
Ta có :
15 : 5 = 3
Mẫu x 3 thì tử cũng x 3 để .....
Ra số cần điền tiếp là 6 ( 6/15 )
Ta có :
20 : 5 = 4
Mẫu x 3 thì tử cũng x 4 để ....
Ra số cần điền tiếp là 8 ( 8/20 )
Tương tự làm câu kia , cần điền :
9 ( 9/12 )
12 ( 12/16 )
15 ( 15/20
\(\frac{2}{5}=\frac{4}{10}=\frac{6}{15}=\frac{8}{20}\)
\(\frac{3}{4}=\frac{9}{12}=\frac{12}{16}=\frac{15}{20}\)
muốn làm sao để ra con số thì bạn chỉ cần quy đồng lên nhé
VD:\(\frac{2}{5}=\frac{2\times2}{5\times2}=\frac{4}{10}\)
\(\frac{4}{10}=\frac{4\times3\div2}{10\times3\div2}=\frac{6}{15}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
12/14 + 15/20 + 6/7 + 3/4
= ( 12/14 + 6/7 ) + ( 15/20 + 3/4 )
= ( 6/7 + 6/7 ) + ( 3/4 + 3/4 )
= 12/7 + 6/4
= 48/28 + 42/28
= 90/28
= 45/14
Tham khảo nha !!!
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a) $\frac{1}{3} + \frac{1}{3} + \frac{1}{6} = \frac{2}{3} + \frac{1}{6} = \frac{4}{6} + \frac{1}{6} = \frac{5}{6}$
b) $\frac{1}{{12}} + \frac{3}{4} + \frac{2}{{12}} = \left( {\frac{1}{{12}} + \frac{2}{{12}}} \right) + \frac{3}{4} = \frac{1}{4} + \frac{3}{4} = \frac{4}{4} = 1$
c) $\frac{{19}}{{15}} + 0 + \frac{{11}}{{15}} = \frac{{19 + 11}}{{15}} = \frac{{30}}{{15}} = 2$
![](https://rs.olm.vn/images/avt/0.png?1311)
a ) \(\frac{4}{7}\) = \(\frac{4\cdot5}{7\cdot5}\) = \(\frac{20}{35}\)
\(\frac{16}{35}\) giữ ngyên
\(\frac{16}{35}\) < \(\frac{20}{35}\) . Vậy \(\frac{4}{7}\) > \(\frac{16}{35}\)
b ) \(\frac{13}{15}\) = \(\frac{13\cdot12}{15\cdot12}\) = \(\frac{156}{180}\)
\(\frac{11}{12}\) = \(\frac{11\cdot15}{12\cdot15}\) = \(\frac{165}{180}\)
\(\frac{156}{180}\) < \(\frac{165}{180}\) nên \(\frac{13}{15}\) < \(\frac{11}{12}\)
=> x/4 = 15/12 - 13/20
=> x/4 = 3/5
=> x = 3/5 x 4
=> x = 12/5
Tk mk nha